The invention proposes a pair of covers to remove electrostatic charges from the surface of a phonograph record and to prevent its deterioration. Phonograph records, which are made of synthetic resin, accumulate electrostatic charges on their surfaces as a result of friction between the needle and the grooves. The electrostatic charges, in turn, attract dust particles to the record's surface. This results in the deterioration of a phonograph record and adversely affects the sound produced from such a record. The damage caused by dust particles to a phonograph record is more serious if the pick-up arm of a phonograph record player is designed to operate below three grams.
Manual handling can also damage the surface of a phonograph record. In particular, when a record is removed, or inserted, from its cover, the dust on the surface acts as an abrasive agent causing surface scratches. Natural oils from the finger tips can also be transferred onto the surface of a phonograph record in the process of handling; this causes further damage to a phonograph record.
In addition, if an automatic record changer is used to play phonograph records, the impact of a falling record can damage the sound track, particularly if a phonograph record is warped. Also, dust particles trapped between the surfaces of two phonograph records being played on an automatic changer act as abrasive agents scratching the surfaces in their contact.
Finally, in the course of playing a phonograph record, both of its surfaces are exposed to dust and other sources of contamination; when in fact, for the purpose of reproducing sound, it is necessary that only the surface in contact with the needle be exposed. The unnecessary exposure of the recorded surface, not being used to reproduce sound, to dust and oil increases the probability of surface damage.
It is of prime importance in keeping phonograph records in good condition and to produce good undistorted sound that the surfaces of phonograph records are kept free of electrostatic charges, dust, oils, etc., and the exposure to the record's surface not being used for the reproduction of sound be curtailed.
The antistatic films applied to the surface of a phonograph record, in the form of sprays or lotions, to prevent electrostatic charges have indicated problems in their use. In particular, if the pick-up arm of a record player operates below three grams, the needle presses with such small force along the groove that it is unable to displace the leftovers of antistatic film. Consequently, the needle skates over the sound track resulting in the distortion of sound. Other devices, for example parastat and dust-bug are also available as means to remove static electricity from the surface of a phonograph record. Both of these devices require moisture to provide a leakage way for electrostatic charge; some of the moisture may be transferred to the surface of a record and can produce the skating effect discussed earlier.
A number of devices are available to remove dust from the surface of a phonograph record. Nevertheless, deterioration of phonograph records cannot be prevented with such devices. These devices, it should be noted, are meant to be curative rather than preventive against damages to a record's surface; but, microgrooves and sophisticated pick-up system make it necessary for reproducing good undistorted sound that dust and other damaging materials be not allowed to accumulate on a record's surface in the first place.
Therefore, in order to reproduce undistorted sound from a phonograph record, it is essential that a record's surface be (1) without electrostatic charges, (2) free of dust, grease, etc., and (3) should be protected to prevent surface scratches during normal use and handling. A cover which is designed to achieve these desired results, along with an attractive and durable surface which can be used to print information and displays, is the central object of this invention.